Thermostatic overload switch



AprilZl, 1936.

FLJ.HAMMERLY Filed Dec. 24, 1934 HERMAN THERMOSTATI C OVERLOAD SWITCHPOI 2 Sheets-Shet 1 INVENTOR J.HAMMERun April 1936. H. J. HAMMERLY2,038,105

THERMOSTATIC OVERLOAD SWITCH Filed Dec. 24, 1954 2 Sheets-Sheet 2 IPatented Apr. 21, 1936 UNITED STATES THERMO STATIC OVERLOAD SWITCHHerman J. Hammerly,

New Britain, Conn, as-

signor to The Trumbull Electric Manufacturing Company, Plainville, Conn,a corporation of Connecticut Application December 24, 1934, Serial No.758,913 F Q l L. at 14 W L 11 Claims. (Cl. 200-116) My invention relatesparticularly to electric switches adapted to be normally manuallyactuated but which will automatically open the circuit in case of anoverload.

5 One object is to provide an extremely simple and practicalconstruction of the snap action toggle type which is automaticallyreleased by the action of a thermostatic strip to open the circuit incase of an overload. The switch is normally actuated to off and onpositions by the simple tilting of a finger lever. A bimetallicthermostatic strip in the form of a latch holds the parts when they aremoved to the closed circuit position. The removable and renewable heaterunit coacts with the thermostatic strip to release the toggle action incase of an overload. The switch may then be reset manually as soon as itis cooled off.

The exact form of embodiment is notvital to the invention.

Fig. 1 shows a front view of one form of construction embodying myinvention.

Fig. 2 shows a vertical section and side elevation with the parts in theoff or open circuit 26 position.

Fig. 3 is a rear view.

Fig. 4 is a transverse sectional view on the plane of the line 4-4 ofFig. 1.

Fig. 5 is a vertical sectional view on a some- 30 what difierent planefrom that of Fig. 2 but also showing the parts in the open circuit orofl po-- sition and omitting the box part of the housing.

Fig. 6 is a similar sectional view showing the parts in the on or closedcircuit position.

35 Fig. 7 is a fragmentary view showing the parts in the position whichthey occupy when released thermostatically.

Fig. 8 is an exploded perspective view showing parts of the switchmechanism.

The switch shown is of the enclosed snap action type. The housing ismade up of the base or front section l0 and the box like portion bothformed of insulating material and held together by a number of screws l3which screw into the face plate l2. The binding post or terminal I4 iselectrically connected to the spring switch arm I5, the movable end ofwhich coacts with the stationary contact l6. 2

The terminal [1 is electrically connected to the 50 spring switch armI8, the movable end of which is adapted to engage the stationary contact|8.

These two arms I5 and I8 are mechanically connected by an insulatingcross bar 20.

The operating lever 2| carries a metal U-shaped 55 member with hingepins 22 which are pivotally supported in the bearing openings 23 in theside arms 24 of the bracket or frame of which the front plate 92 is apart.

The toggle link 25 has hinge members 26 pivoted in the openings 2'! inthe inner ends of the arms 24. The end 28 of the toggle member 25 has ahinge-like connection in the end of the slotted bar 29 which looselyslides in the handle 2| in the usual manner. The swinging movement ofthe lever 25 is limited by the projection 30 which extends into the slot3| in one of the arms 24 of the frame. The spring 32 is mounted on theslotted bar 29 and presses against the washer 29' so as to snap thelever 25 back and forth as the finger piece 2| is actuated.

The bimetallic thermostatic latch member 33 is supported by the post 34.The catch member 35 is hinged in the lugs 36 which form a part of thetoggle member 25. One end 31 of the catch 35 is adapted to coact withthe hook of the latch 33 and the other end 38 coacts with the cross bar20 of the movable switch member. The cross piece 39 serves as anabutment or stop for the finger part 38 of the catch member 35.

The action of the switch under normal load conditions is very much thesame as that of a conventional type toggle switch. In other words, whenthe switch is ofi or in the open circuit position of Fig. 5 the circuitmay be closed by simply lifting the finger piece 2| sufiicie'ntly sothat the cross piece 28 of the toggle link 25 comes below the centerline whereupon the toggle action closes the circuit. The opening of thecircuit is effected by moving the finger piece 2| in the reversedirection whereupon the snap action of the toggle takes place aided bythe spring action of the arms l5 and |8.

The resistance or heater unit 4|! may be formed from a flat stamping orflattened wire formed into a coil or zigzag shape and secured in placeby screws 4| and 42. The screw 4| is threaded into one end of thebracket 43 which is connected to the terminal H. The screw 42 isthreaded into the bracket 44 which has the circuit terminal 45 at thefront. The plate 46 of mica or other suitable insulating material isinterposed between the heater or resistance unit and the thermostaticlatch 33.

A screw 4.1 may be provided for adjusting the position or action of thelatch 33. An indicator strip 48 has one end, supported by the plate 48and the other end extended through the base l0 and exposed at the frontwith a mark indicating the rating of the capacity of the switch.

When the switch is in the closed circuit position as shown in Fig. 6 thelatch 33 engages the beveled tip 31 of the catch member and is heldthere by the spring pressure or bias of the arms l5 and I8 through thecross bar 20 which presses upon the tail 38 of the catch and tends torotate the catch member clockwise as viewed in Fig. 6.

When the thermostatic latch member is heated by an overload current itwarps or bends so that its hook-like tip will be disengaged from the tip31 of the catch and thus allow the spring arms l5 and iii to tilt thecatch into the position shown in Fig. 7, thus opening the circuitwithout affecting the toggle action. To reset the switch it is merelynecessary to tilt the finger piece 2| from the position of Fig. 6 to theposition of Fig. 5 which throws the catch back into the position shownin Fig. 5.

From the foregoing it will be seen that the switch may be actuatedmanually under normal circumstances in the same manner as any toggleaction switch. It will also be seen that under overload conditions theheater unit will cause the thermostatic switch to warp and release thefiipper or catch which in turn allows the movable switch members to openthe circuit even though the operating handle is held in the on position.The catch or flipper hasno spring of its own but its movement is causedby the action of the spring 32 and the spring arms I5 and I8 abovedescribed.

One of the important novel features in this present invention is thefreely mounted flipper or catch member which requires no spring of itsown and functions as a latching or catch member.

It will be further seen that the normal toggle action is whollyindependent of the thermostatic action. The resistance heater unit isdetachable and can be readily replaced. Obviously the same mechanism maybe employed for different capacities by the simple expedient of properlydesigning the thermostatic latch and the heater unit.

I claim:

1. In a toggle action thermostatic switch, an insulating support, ametal frame carried thereby and having a toggle action device, a freelypivoted catch carried by one part of the toggle action device and athermostatic latch coacting with the catch.

2. In a toggle action switch, a spring switch arm, a toggle actiondevice including a catch carried by one part of the device and coactingwith the spring switch member and a thermostatic latch coacting withsaid catch.

3. In a toggle action thermostatic switch, a metallic frame, a togglelever hinged at one end of the frame, a finger piece hinged to thetoggle member, a spring for biasing the toggle member, a catch looselyhinged to the toggle member, a spring pressed switch member moved in onedirection by the catch and a thermostatic latch coacting with said catchto permit the normal opening and closing of the switch but adapted torelease the toggle action in case of an overload.

4. In a thermostatic switch, a toggle action device, a freely pivotedcatch carried by one part of the toggle action device and a thermostaticlatch coacting with the catch and a spring pressed switch membercoacting with said catch.

5. In a toggle action switch, a spring switch arm, a toggle actiondevice including a catch pivoted to one part of the device and coactingwith the spring switch arm and a resilient thermostatic latch coactingwith said catch.

6'. In a toggle action thermostatic switch, a metallicframe, a togglelever hinged at one end to the frame, a finger piece connected to thetoggle member, a spring for biasing the toggle member, a catch hinged tothe toggle member, a spring pressed switch member moved in one directionby the catch and a resilient thermostatic latch coacting with said catchand adapted to release the toggle action in case of an overload.

'7. An electric switch including a pivoted operating lever, a pivotedtoggle member hinged to the operating lever, a catch member hinged tothe toggle member, a spring pressed switch member coacting with thecatch member and a thermostatic latch normally interposed in the path ofthe catch member.

8. A snap switch including a stationary contact, a movable contact forcoacting therewith and normally biased to the oil position, operatingmechanism coacting with the movable member and including a finger lever,an oscillating member connected to the finger lever, means pivotallycarried by the oscillating member and free to move on occasion of anoverload, a thermal element holding said means under normal circuitconditions and a throwing spring coacting with the oscillating memberfor actuating the same and the said means carried thereby so as to openand close the circuit with a snap action when said finger lever ismanually operated and so as to open the circuit with a snap action whenthe thermal element releases said means.

9. In a snap switch, an insulating support having a passage extendingfrom front to rear of said support, a stationary contact and acooperating movable contact carried by said support, said movablesupport being biased to an open circuit position, a thermally actuatedelement carried by the support, a frame secured to said support andhaving ears projecting into said passage, a finger lever pivotallycarried by said ears, an oscillating member pivotally carried by andrestricted in its movement by said ears, a latching member pivotallycarried by said oscillating member and free to move on occurrence of anoverload in the circuit, one end of said latching member being held bysaid thermally actuated element under normal circuit conditions andadapted to be released by the action of the thermally actuated elementupon an overload condition, the other end of said latching membercoacting with the movable contact so that the movable contact may bemoved by the action of the finger lever to open and close the circuit.

10. In a snap switch, a stationary contact, a movable contactcooperating therewith and normally biased in an off position, anoscillating member, a finger lever connected to the oscillating member,a throwing spring interposed between said finger lever and saidoscillating member, a latching member mounted on said oscillating memberand coacting with the movable switch element to operate the same whenthe finger lever is manually operated to open and close the circuit, anda thermally actuated member holding said latching member under normalload circuit conditions and adapted to release said latching member onan overload condition, said spring actuating the oscillating memberWhenthe thermally actuated element releases the latching member and saidspring also actuating the oscillating member when the finger leverstarts the oscillating member.

11. A snap switch construction of the manual and automatic overloadtype, including a stationary contact, a movable contact cooperatingtherewith and normally biased to the open circuit position, an operatingunit including a finger lever, an oscillating member connected thereto,a combined cam and latching member pivotally mounted on and carried bysaid oscillating member and serving to hold the movable contact in theclosed circuit position and free to move on occurrence of an overload inthe circuit, a thertion and a throwing spring interposed between saidfinger lever and said oscillating member for opening said switch with asnap action during normal circuit conditions and also for opening theswitch with a snap action on an overload condition.

'HERMAN J. HAMMERLY.

